1. Field of the Invention
This invention relates to a gas-discharging passage of storage battery and a molding method thereof. More particularly, the present invention relates to improvements in the construction of a gas-discharging passage of the storage battery which is formed with, especially, a proper molding material through a molding operation, in the productivity of the molding method, and in the prevention of the electrolyte leakage.
2. Description of the Prior Art
Conventionally, a passage was formed in the storage battery to discharge the gas produced during a charging operation. The passage was designed to prevent the electrolyte leakage, which was caused due to the vibration of the storage battery or the oscillation thereof, or the evaporated electrolyte from being scattered outwardly. Accordingly, various passage shapes were proposed. Most of the conventional passage shapes were complicated or suitable barriers were provided in the passage to avoid the above disadvantages. Accordingly, most of such passages became complicated in construction. Complexity was involved in the processes of manufacturing, since a plurality of parts were required to be molded individually and then to be integrated with bonding agent, etc.
The integration by the use of the bonding agent, etc. will be described hereinafter. Olefin resin such as polypropylene resin which is superior in oil resistance and chemical resistance is recently used as an electric cell material for the storage battery. However, for example, the polypropylene, etc. have an extremely inferior adhesive property when the bonding agent is used for them. Accordingly, when such synthetic resin as the polypropylene resin which is inferior in adhesive property is used as the electric cell, it is advantageous to avoid the assembling operation with bonding agent if possible or completely during the manufacturing processes. As apparent from the foregoing description, when the gas-discharging passage of the storage battery which is made of such synthetic resin as the polypropylene resin is formed, the assembling process in which a plurality of parts are molded individually and thereafter are integrated through the bonding should be avoided as much as possible.
In addition to the problems caused during the manufacturing processes described hereinabove, the electrolyte may scatter due to the vibration of the storage battery or the oscillation thereof or the evaporated electrolyte may be condensed where the passage for gas-discharging is narrow or complicated. Thus, the electrolyte may remain in the passage and may be forced out through the pressure of the gas produced during charging operation, thus resulting in leakage of the electrolyte. Accordingly, it is desirable to provide such passage shape as the electrolyte in the gas-discharging passage may drip to return to the electric battery.